package org.wanda.pv.util;

public class ExcelColumn {
  public static void main(String[] args) {
    /*String colstr = "AA";
    int colIndex = excelColStrToNum(colstr, colstr.length());
    System.out.println("'" + colstr + "' column index of " + colIndex);
    colIndex = 26;
    colstr = excelColIndexToStr(colIndex);
    System.out.println(colIndex + " column in excel of " + colstr);
    colstr = "AAAA";
    colIndex = excelColStrToNum(colstr, colstr.length());
    System.out.println("'" + colstr + "' column index of " + colIndex);
    colIndex = 466948;
    colstr = excelColIndexToStr(colIndex);
    System.out.println(colIndex + " column in excel of " + colstr);*/
    String s = excelColIndexToStr(27);
    System.out.println(s);

  }
  /**
   * Excel column index begin 1
   * @param colStr
   * @param length
   * @return
   */
  public static int excelColStrToNum(String colStr, int length) {
    int num = 0;
    int result = 0;
    for(int i = 0; i < length; i++) {
      char ch = colStr.charAt(length - i - 1);
      num = (int)(ch - 'A' + 1) ;
      num *= Math.pow(26, i);
      result += num;
    }
    return result;
  }
  /**
   * Excel column index begin 1
   * @param columnIndex
   * @return
   */
  public static String excelColIndexToStr(int columnIndex) {
    if (columnIndex <= 0) {
      return null;
    }
    String columnStr = "";
    columnIndex--;
    do {
      if (columnStr.length() > 0) {
        columnIndex--;
      }
      columnStr = ((char) (columnIndex % 26 + (int) 'A')) + columnStr;
      columnIndex = (int) ((columnIndex - columnIndex % 26) / 26);
    } while (columnIndex > 0);
    return columnStr;
  }
}